Defending Science-Based Water Protections

In October 2025, the U.S. EPA approved Montana’s repeal of its science-based numeric nutrient standards, replacing them with vague, narrative criteria that only identify pollution after damage occurs. This change, passed through House Bill 664, removed clear limits for nitrogen and phosphorus, two of the most common pollutants entering our waterways from fertilizers, livestock waste, and wastewater discharges. Numeric standards once allowed regulators to detect and reduce nutrient pollution before algae blooms, fish kills, and other harmful impacts took hold. Without them, Montana’s clean-water laws now rely on subjective language that makes early intervention nearly impossible.

The Flathead Lakers and partner organizations have filed a Notice of Intent to Sue the EPA to defend Montana’s right to measurable, enforceable water protections. EPA’s approval marks a sharp reversal from its own 2022 decision rejecting a similar rollback and comes even as over 7,200 miles of rivers and one-fifth of the state’s lakes are already impaired by nutrient pollution. The result is a regulatory void that jeopardizes the health of Flathead Lake, threatens endangered species such as bull trout, and endangers Montana’s $1.3 billion cold-water fisheries and outdoor recreation economy.

Flathead Lakers are calling on state and federal leaders to restore science-based water standards before further harm occurs. We urge Montana DEQ to pause new permit approvals until a credible, science-based narrative nutrient rule package is developed—one that provides clear metrics for protecting and restoring local water quality. Your continued support ensures that the Flathead Lakers can stand strong in court and in the community to keep Flathead Lake and Montana’s waters clean, healthy, and thriving for generations to come.

Join your neighbors, businesses, and fellow Montanans in asking DEQ to do the right thing, use common sense, and pause new decisions until it adopts a narrative nutrient replacement rule.

Sign the Petition

FAQs: Montana’s Rollback of Numeric Nutrient Water Quality Standards

5 Things to Know About Montana’s 2025 Repeal of Numeric Nutrient Water Protections